Such a charging system as will be described below is known. Namely, this charging system includes: power transmitting means; power receiving means for receiving an electric power from the power transmitting means in a contactless manner; efficiency detecting means for detecting a transmission efficiency between the power transmitting means and the power receiving means; determining means for determining whether the detected transmission efficiency is equal to or larger than a prescribed value; and control means for determining that a normal power supply is obstructed by means of an obstacle or so forth in a case where the transmission efficiency is below the prescribed value, for temporarily stopping the power transmission by means of the power transmitting means, and for restarting the power transmission through a minute electric power after a prescribed time (Patent Document 1).
However, since, in the above-described Patent Document 1, the transmission efficiency is calculated from the received electric power of the power receiving means, the transmission efficiency cannot be calculated in a case where an electric current of the power receiving means cannot be measured.